Latency, error finishing read, and IRQ affinity

mozmck wrote:

It should be run from /etc/rc.local and not as a policyscript for irqbalance.

Ah. You actually did mentioned, missed it, sry. 

What's the required voodoo to verify/debug besides $ watch -n1 -d cat /proc/interrupts ? 

tommylight wrote:

Made this sticky, thank you.

If this is stickied now, is this the right section? It might be better in Installing linuxcnc

mozmck wrote:

I haven't tested it myself yet, but I know I have a dual-core or two around here that I can try it on. Probably be next week or so before I can find time to do that.
 

(my take:) I wouldn't bother spending time on those expired dual-core dinosaurs, @mozmck. As soon as you "isolcpus=1" this in grub you instantly lose irqbalance. The service won't even start regardless if the script is ran from a policy or by using rc.local custom/adapted script from rc.local. 

One thing for sure, this hack works flawlessly for =>4 cores cpus. Remarkable enhancement I'd like to add. Recommend!!! 

rodw wrote:

If this is stickied now, is this the right section? It might be better in Installing linuxcnc

That or "driver boards", what would be more appropriate?

Should probably be added to official docs..

Here is a script which will do the following:

1. Set up isolcpus and a couple of other kernel arguments
2. Run update-grub
3. Create the IRQ affinity policy script for irqbalance
4. Set up irqbalance to use the script.

There are a few kernel options that *might* be helpful in reducing latency that can be enabled by uncommenting the relevant sections.
There are a couple of lines at the end which disable syncing the system clock to internet time servers.  This syncing has in the past been one cause of realtime errors.  This might should be made default???

To use, save the script as "rt_setup", make it executable, and run it with sudo because it needs root privileges. Then you'll need to reboot the PC.

One improvement would be to detect dual-core systems or ones without irqbalance and do something different for the IRQ affinity.

****** UPDATE ******
I updated this script and moved it to the first post in this thread.

 
I got the error in the picture. can't find folder

Ekholm wrote:

I got the error in the picture. can't find folder

 

Is irqbalance installed? - Oops, should have refreshed the page before sending.  I don't know where else the config file for irqbalance would be than /etc/default
What linux distribution are you running?

mozmck wrote:

Something like this should work:

Code:

#!/bin/bash MASK=$( printf "%X" $((1<<`lscpu -e=CPU | tail -1`)) ) NIC=`awk 'BEGIN{nic=""} {if ($1=="iface") {tmpnic = $2} if ($1=="address") {if ($2 == 10.10.10.1) {nic = tmpnic}}} END{print(nic)}' /etc/network/interfaces` if [ "$NIC" != "" ]; then     grep $NIC /proc/interrupts | cut -d ":" -f 1 | while read -r IRQ; do         echo $MASK > /proc/irq/$IRQ/smp_affinity     done fi exit 0"

 

quotes seem to be missing here?  ($2 == 10.10.10.1) →→→ ($2 == "10.10.10.1")